how to count number of rise and fall in voltage level

[anamikatripathi]

electronic stethoscope. need little hepl

i am designing a stethoscope based on measuring blood density at particular part of body as the density rises voltage level is 10v as density falls voltage falls to 6v i want to count the total number of rise and fall. if some1 can help me out in it its quite urgent i will be greatfull to you

 

[Grossel]

You can connect it to a derivator and then to a schmitt trigger where zero voltage is between the lower and upper trigger level. It takes two opamps.

After that you can use two monostable latches, one that activate at rising edge, and the other activates at falling edge. Each monostable latch outputs can connect to it's respective counter.

 

[anamikatripathi]

thanks but i am just a starter and i think using schmitt trigger will make circuit complicated can u send me link so that i can check and is there anything available in form of chip. or can we use threshold detector

 

[anamikatripathi]

thanks it will work and i m great ful to u

 

[Grossel]

Sounds like you want somebody to design this for you. A schitt-trigger isn't a complicated thing.

Read about:
Inverting differentiator
Schmitt trigger
**broken link removed** Look at the middle of the web page. It's a really simple circuit.

 

[anamikatripathi]

i have done it and thought about using timer 555 and counter of pic16fxx micro controller will it work

 

[blueroomelectronics]

Don't need a 555 if you've got a PIC.